I'm a bit biased since I'm a core developer with SilverStripe but from my experience using Wordpress (also was quite deep with that) SilverStripe has a much nicer architecture and much easier to extend. Wordpress doesn't feel as well designed as some of SilverStripe (in terms of software design, not UI). Although if you want to easily build large websites to work out of the box you would be better to stick with the other platforms.

With SilverStripe if you have a general understanding of OOP PHP and willing to get stuck in you'll reap the rewards.

Just curious, when you mention that I might want to stick to other platforms when looking to build large websites straight out of the box. Any chance you could eleborate?

I mean take Wordpress if you want to run multiple blogs, have sidebars everywhere and widgets it handles that out of the box with very little effort (point, click, drag) and anything else you need is usually covered by a plugin. You can get away with a very low level of PHP knowledge and simply feel you way through wordpress without understanding the deep workings.

SilverStripe is targeted more towards developers than the casual user/blogger so you will have to get your hands dirty into creating php files, building functions to fill in the gaps. Saying that the forum is always keen to help out on the hard stuff!

Best option is to try out the tutorials, build a couple simple sites and see how it goes for you!

I tried Silverstripe and Wordpress, but I like more SilverStripe than Wordpress because in SS is more simple to build a site and css layout and I think that SS is more applicable for various web apps...With WP is like a square that would became a circle...

As Willr said, SilverStripe is targeted more at developers, so knowing PHP is generally a requirement for using SS.

SS strikes me as a step or two above a framework. You're given a framework (in this case, Sapphire), a template system, and a basic architecture with a few pages started for you. What's there can get you up and running quickly if you're just tossing something together quickly for whatever reason and don't really need to do any customization. Where you go from there is pretty much entirely up to you, since you then build from that. Whether this is a good thing depends entirely on your level of experience with PHP and OOP (for you, specifically, it's probably a good thing), as well as the scope of a given project in question.

What I also love, too, is the community. SilverStripe has a smaller community than some of the other big projects, but as you can see, there's a lot of involvement from the people that actually maintain the core. If you post a coherent question on the forums, you're very likely to get a response, often by the people that created the portion in question (for example, if you have a question about the SWF file uploader, you'll likely get a response from its creator, Uncle Cheese). I've even seen devs responding to people that had questions or criticisms in other blogs, which is rare in my experience.

I used to use Wordpress quite a bit. It is great if you want to throw together a site and aren't to worried about the design of the front end. Also, if any, more advanced functionality can be achieved solely through using plugins, then Wordpress is pretty good.

The trouble comes when you want to add functionality above the default plugins. In Wordpress, this is an absolute nightmare. Usually you have to download a plugin that closest matches what you want, hack it about abit, and then load it into your site. Then, if you want to keep that plugin upgraded, you have to go about the same process each time.

Silverstripe lets you extend current modules, or create your own really easily. But its architecture is very different to Wordpress. Like has been mentioned, Silverstripe is basically a framework, with an advanced CMS scaffold built on top. It is more like other well known frameworks, like Ruby on Rails or Django.

Pleasantly suprised at how quickly I was able to implement the a sliced up version of the clients website into SilverStripe.

Theres only one thing that I'm sort of struggling with at the moment and that is displaying the content from two different page types in a holder.

For example, displaying the first paragraph from the "About Us" page in the bodies left column and a collection of excerts of the latest testimonials in the right column but I might start a new thread to ask that question, along with a few extra details.